With just one month to the close of 2015, Southport, Connecticut-based Astenbeck was down 26.3 percent on the year, according to monthly data sent by the fund to investors and seen by Reuters.

Astenbeck has been trading since 2008 and its sharpest annual decline before this was 8 percent, in 2013. Its losses for November mirrored the 10 percent drop last month in prices of global oil benchmark Brent and U.S. crude.

The fund’s slide appears to have eaten into the money managed by the 64-year-old Hall, a renowned trader who earned a $100 million bonus from Citigroup for right calls made on oil when he worked with the Wall Street firm before the financial crisis.

The data sheet obtained by Reuters showed assets under management at Astenbeck having fallen to about $2.4 billion, from about $3 billion reported at the start of the year.

In a letter to Astenbeck’s investors that accompanied the performance data, Hall said he was not ready to give up his bullish stance on oil yet.

“There is certainly still a chance of lower prices in the next month or so,” he wrote. “But weighing that possibility against the virtual inevitability of higher prices down the road leads to a simple conclusion: now is not the time to exit the market.”

Astenbeck has only posted four positive months of returns this year as the stubborn oversupply in oil forced crude prices to lows last seen during the 2008/09 credit crunch.

Brent broke below $40 a barrel on Tuesday, while U.S. crude under $37 on fears the world will run out of storage space for oil from an intensifying supply glut after a OPEC meeting last week all but abandoned price support measures.

A year ago, Brent and U.S. crude were trading at around $60, and during early summer 2014, above $100. Banks such as Goldman Sachs have said oil could fall to $20.

“This in turn provoked press reports of queues of oil tankers waiting to discharge, adding to the gloom and resurrecting fears of the industry running out of storage,” he wrote. (Reporting By Barani Krishnan; Editing by Alan Crosby)